1. Field of the Invention
The present invention relates to a germicidal ceramics, a method for producing the same, and a sterilizing method using the same.
2. Description of the Related Art
Generally, water is purified and sterilized before it is supplied to the public as tap water. In the purification process, undesirable impurities are removed from the water. In the sterilization process, sodium hypochlorite is often used as a germicidal agent for killing the remaining bacteria.
However, in recent years, it has been pointed out that the sterilized water is not good for the human health since chlorine liberated from sodium hypochlorite exists in such water.
Chlorine is widely known as a toxic substance. If chlorine of high concentration is ingested by a person, some health problems are likely to occur. For example, the mucous membrane of lungs, nostril or the like is damaged. Even if the chlorine concentration in water is low, assuming that the water is repeatedly ingested by a person for a long period of time, health problems such as arteriosclerosis may occur.
Further, if the liberated chlorine is reacted with an organic matter remaining in tap water, it generates carcinogenic methane trihalide (trihalomethane). It is not favorable for the health to ingest the water containing the carcinogenic substance.
Thus, there is a problem that it is not favorable for the human health to sterilize the tap water with sodium hypochlorite.
Accordingly, it is assumed to solve the above problem by using a substance other than sodium hypochlorite as the germicidal agent.
However, an alternative germicidal agent has not yet been found so far which is excellent in germicidal ability against pathogenic Escherichia coli such as O-157 known to cause food poisoning and which is harmless to the human body.
The present invention has been made to solve the above problems. It is an object of the present invention to provide a germicidal ceramics which fast sterilizes bacteria such as Escherichia coli without releasing any substance to damage health of animals and plants and to provide a method for producing the same and a sterilizing method using the same.
The present invention provides a germicidal ceramics comprising 50 to 90 parts by weight of zeolite powder and 50 to 10 parts by weight of clamshell powder, the zeolite powder and the clamshell powder being sintered.
It is another aspect of the present invention to provide a method for producing a germicidal ceramics; comprising a mixing step of mixing zeolite and clamshell in a weight ratio of 90:10 to 50:50 and then pulverizing the both to have an average particle size of not more than 200 xcexcm, or mixing, in a weight ratio of 90:10 to 50:50, zeolite powder and clamshell powder previously pulverized to have an average particle size of not more than 200 xcexcm respectively to prepare mixed powder; a compacting step of compacting the mixed powder to prepare a compact; a water-removing step of heating the compact at 100 to 300xc2x0 C. to remove water from the compact; a subsequent gas/remaining water-removing step of heating the compact at 400 to 650xc2x0 C. so that carbon dioxide gas can be generated from the clamshell to volatilize and remove the carbon dioxide gas from the compact, and any water remaining in pores of the zeolite is removed; and a heating step of heating the compact at 700 to 1050xc2x0 C. to sinter the compact so that a sintered compact can be prepared.
It is still another aspect of the present invention to provide a sterilizing method for sterilizing bacteria by immersing, in a liquid in which the bacteria exist, a germicidal ceramics comprising 50 to 90 parts by weight of zeolite powder and 50 to 10 parts by weight of clamshell powder, the zeolite powder and the clamshell powder being sintered.
In the present invention, natural zeolite is preferably used as the zeolite, and at least one of oyster shell and scallop shell is used as the clamshell.